New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName:'Ember Twiddle',
  isAdministrator: false,
  notAdministrator: Ember.computed.not('isAdministrator')
});

helpers.not.js

import Ember from 'ember'

export function not(params) {
  return !params[0]
}

export default Ember.HTMLBars.makeBoundHelper(not)

router.js

import Ember from 'ember';
var Router = Ember.Router.extend({
  location: 'none'
});

Router.map(function() {
});

export default Router;

templates.application.hbs

<h1>Arbitrary Expressions in HTMLBars</h1><br><br>

<p>
You cannot have arbitrary expressions in HTMLBars/Handlebars such as <code>!</code>. There are two good approaches to this problem, a computed macro or a <code>not</code> helper.
</p>

<p>
Toggle isAdministrator? {{input type='checkbox' checked=isAdministrator}} (value: <code>{{isAdministrator}}</code>)
</p>

<p>
	<h3>Take 1: Ember computed macro</h3>
	<p>This uses a computed macro called <code>notAdministrator</code> that is the inverse of <code>isAdministrator</code>. See the Controller where it is defined.</p>
	<input type='checkbox' disabled={{notAdministrator}}>
  <button disabled={{notAdministrator}}>Am I an admin?</button>
</p>

<p>
	<h3>Take 2: <code>not</code> helper</h3>
	<p>This uses a helper called <code>not</code>. It makes it easy to compose these type of expressions in your template. See <a href='https://github.com/jmurphyau/ember-truth-helpers'>ember-truth-helpers</a>.</p>
	<input type='checkbox' disabled={{not isAdministrator}}>
  <button disabled={{not isAdministrator}}>Am I an admin?</button>
</p>